Friends share similar genes suggests new study

People with shared genes are apparently more likely to form friendships than people whose individual DNA’s are dissimilar finds new study.

A new study suggests friends share certain genetic compatibility similar to that of fourth-generation cousins. Photo: Thomas Appleby

The research, published in the journal Proceedings of the National Academy of Sciences (PNAS) was carried out collectively by two professors, James Fowler of the University of California in San Diego and Nicholas Christakis at Yale University.

The study looked into the DNA of 1,932 candidates, who had participated in the 1948 Framingham Heart Study, which has produced one of the largest data recorded for both gene information and details of social relationships.

The scientists compared the DNA of pairs of individuals depending on whether they were friends or perfect strangers. It was found that while there were no significant similarities between those who had never met, pairs of friends were seen to share around one per cent of gene mutations.

Professor Christakis remarked: “One per cent may not sound like much to the layperson, but to geneticists it is a significant number.”

Experts believe two friends might be just as related to each other as they would be to their respective fourth cousins, or rather those with whom they share a great-great-great-grandparent.

For both Fowler and Christakis, the results of the study support their notion that friends serve as a kind of “functional kin”. The professors believe that “one’s friends may evince a kind of functional relatedness” and that two people might relate as friends because in social and environmental terms they are mutually beneficial to one another.

The study also found that the observed correlation between friends and people who share genotypes may significantly affect other “biological and social processes, from the spread of germs to the spread of information”.

In their conclusion, Fowler and Christakis suggested: “The human evolutionary environment is not limited to the physical environment (sunshine, altitude) or biological environment (predators, pathogens) but also includes the social environment, which may itself be an evolutionary force.”

The report suggests that the human capability to bond not only with kin but also with unrelated members of the society may have noticeably “increased the potential gains of synergy”. The change not only favours interactions with similar partners, but also affects the overall desire to search for such partners, thus the process could speed up evolution of phenotypes that are “intrinsically synergistic”. Scientists think these findings would therefore help to explain the acceleration of evolution in humans.